Yeah this has happened to me a few times in the old part of our house, which dates back to the 1600s so make of that what you will. The breathing is the unsettling bit isn't it - not footsteps or bangs, those you can usually explain away. But rhythmic breathing in an empty room at 2am is hard to rationalise.
First time I heard it I genuinely stood in the doorway for about a minute just listening. It had a kind of slow, laboured quality to it. Not threatening exactly but deeply uncomfortable. My dog refused to go in that room for about three days after.
I've read that infrasound can sometimes create sensations that mimic breathing or presence, but honestly that feels like a bit of a stretch for what I heard. Some researchers think residual hauntings can manifest as sound before anything visual develops.
Anyone else noticed a pattern with when it happens - certain times, certain weather, anything like that? Would be useful to compare notes.